* Range values for V4L2_CID_* commands
@ 2020-07-10 14:18 Lucas
2020-07-10 14:28 ` Hans Verkuil
0 siblings, 1 reply; 3+ messages in thread
From: Lucas @ 2020-07-10 14:18 UTC (permalink / raw)
To: linux-media
Hello, how do I obtain the accepted range of values for each V4L2_CID
command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is
the maximum and minimum values accepted for it? I have tried to use
'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored
in the maximum and minimum members for the struct v4l2_queryctrl but
that does not appear to be the case as the values for those members are
always zero.
Thank you.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Range values for V4L2_CID_* commands
2020-07-10 14:18 Range values for V4L2_CID_* commands Lucas
@ 2020-07-10 14:28 ` Hans Verkuil
2020-07-10 14:36 ` Lucas
0 siblings, 1 reply; 3+ messages in thread
From: Hans Verkuil @ 2020-07-10 14:28 UTC (permalink / raw)
To: Lucas, linux-media
On 10/07/2020 16:18, Lucas wrote:
> Hello, how do I obtain the accepted range of values for each V4L2_CID
> command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is
> the maximum and minimum values accepted for it? I have tried to use
> 'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored
> in the maximum and minimum members for the struct v4l2_queryctrl but
> that does not appear to be the case as the values for those members are
> always zero.
Use VIDIOC_QUERYCTRL for that. See:
https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/vidioc-queryctrl.html
Regards,
Hans
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Range values for V4L2_CID_* commands
2020-07-10 14:28 ` Hans Verkuil
@ 2020-07-10 14:36 ` Lucas
0 siblings, 0 replies; 3+ messages in thread
From: Lucas @ 2020-07-10 14:36 UTC (permalink / raw)
To: Hans Verkuil, linux-media
Thank you kind sir.
On 10/07/2020 11:28, Hans Verkuil wrote:
> On 10/07/2020 16:18, Lucas wrote:
>> Hello, how do I obtain the accepted range of values for each V4L2_CID
>> command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is
>> the maximum and minimum values accepted for it? I have tried to use
>> 'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored
>> in the maximum and minimum members for the struct v4l2_queryctrl but
>> that does not appear to be the case as the values for those members are
>> always zero.
> Use VIDIOC_QUERYCTRL for that. See:
>
> https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/vidioc-queryctrl.html
>
> Regards,
>
> Hans
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-07-10 14:18 Range values for V4L2_CID_* commands Lucas
2020-07-10 14:28 ` Hans Verkuil
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